Nobody likes looking like a prune and that’s probably why we find wrinkled digits really strange.
Until recently scientists believed the wrinkling may be due to a process called osmosis. According to this theory, water travels through the skin surface into the upper layer of cells, causing them to swell and wrinkle. However, it has been observed that wrinkling doesn’t happen in fingers or toes with certain types of nerve damage. This blows the osmosis theory out of the water!
Instead, these observations have led some scientists to conclude that the process is controlled by our nervous system. According to this theory, signals from the brain make blood vessels under the skin constrict, which causes the upper layer of skin to pucker and wrinkle.
As we have no conscious control of our wrinkling, it appears to be under the control of our autonomic nervous system, which also regulates ‘automatic’ bodily functions such as heart rate, breathing and digestion.
We’re not completely sure, however some studies have shown that our pruned extremities can be useful for gripping wet objects.
It does seem that the process is in some way connected to our evolution. Our ancestors may have benefitted from an ability to gather food more easily in wet conditions. Maybe it gave their feet better grip in the rain or helped them climb over wet slippery rocks to escape from predators.
So next time you see those wrinkles appear on your fingers, don’t turn your nose up, they may have saved your ancient ancestor’s life!